As is well known, prior art valve blocks for glassware forming machines were devised to satisfy the control needs of the automatic machines which, working on the blow-blow or the press-blow method, effected sequentially a plurality of operations for the manufacture of glassware. Said valve blocks consisted in a metal block having suitable dimensions to be installed in the machine for the manufacture of glassware and contained a plurality of air valves which were in turn operated by pistons or like elements which, in turn, were operated by means of pilot valves mechanically actuated by the also well known timer drum, which was designed jointly with said machines to automatically and sequentially effect the necessary operations.
The air power system, however, was inefficient by virtue of the fact that the pilot valves actuated by the timer drum were located at considerable distances from the main valve block which fed the operational air to the various units and mechanisms of the machine, and by virtue of the fact that the pilot air is normally handled under low volume and high pressure, in order to act on the pneumatic valves by means of pistons which have to overcome a lower pressure of the operational air which was handled at great volumes and, hence, this caused delays that, while being of some fractions of seconds, nevertheless constituted a serious disadvantage for an accurate operation of said machines, which work in a very fast manner. Therefore, many of the installations of glassware manufacturing machines were provided with timer drums directly installed on or near the main operational valve blocks in order to actuate by means of cams, and in sequence, a series of pushers which mechanically operated the valves of said block so as to have a practically instantaneous response. All the prior art installations, using machines operated on the basis of the timer drum, that is, on the basis of operational mechanical cams, were therefore highly intricate and inefficient, because any wear of the mechanical moving parts or any change in the glassware forming process, caused considerable delays and overrides, which were very substantial from the point of view of the speed of operation of the machines and thus inadmissible, causing frequent stops in the machine to remedy the defects of the mechanically actuated movable elements of the valve block, inasmuch as the adjustment operation was difficult and dangerous for the operator because it was effected manually and with the machines working.
With the advent of electronic controls which replaced the traditional mechanical timing drum for mechanically actuating by means of a plurality of cams and pistons that in turn actuated the valves of the block of a glassware manufacturing machine, the conditions of operation and efficiency of the process were greatly improved, inasmuch as it was then possible to have recourse to the use of solenoid valves actuated by means of electrical signals from the electronic timer control, in order to handle in the adequate sequence the various valves of the block of the machine, whereby the responses were more accurate and the traditional problem of undue wear of the cams of the drum or of the followers for operating the valves of the machine was avoided, whereby the number of stops for repairs and replacements was decreased considerably, which enabled the glassware manufacturing industry to increase the speed of operation of the glassware manufacturing machines operated by said valve blocks.
For instance, in U.S. Pat. No. 4,162,910, patented July 31, 1979 to Ball Corporation, a device of this character is described, in which the plurality of mechanical air valves of the valve block of a glassware manufacturing machine, particularly of the well known I.S. type, were operated by means of a plurality of mechanical pusher pistons, integrated to a pneumatic pilot cylinder, for the reception of pilot air from a corresponding solenoid valve. A solenoid valve was provided for each piston and, consequently for each individual valve of the block and these solenoids were actuated by means of electrical signals derived from the electronic timer control of the machine. The valve block of U.S. Pat. No. 4,162,910, while considerably improving the actuation as compared to the traditional timer drum, had as its sole purpose the substitution of said timer drum by means of a plurality of solenoid valves actuated by an electronic timer control. The principle of providing mechanical pusher pistons for pushing the actuators of the valve block was however preserved, said pistons having been incorporated in an additional block which contained a plurality of operational chambers for the pistons, which were arranged angularly with respect to the air ducts from the solenoid valves, whereby the arrangement was relatively intricate. It was also necessary to attach, to the already existing valve block in the glassware forming machine, an additional block of a considerable size, in which all the chambers for the pistons were contained as well as the tubes for feeding pilot air and for carrying pilot air towards the pistons operated by the solenoid valves which had also to be accommodated in the neighborhood of said block, thus rendering the installation and adaptation of said device to the existing glassware forming machines extremely difficult. As the operation of the valves of the block was still effected by mechanical means, namely, by pushers pneumatically actuated by the pilot air from the solenoid valves in accordance with the above explanation, said pushers had to be necessarily contiguously installed with the valve members of the block and aligned therewith, which caused numerous problems of installation which even led to severe modifications of the machines, whereby said technological advance had not a great acceptance. That is, in the particular instance an additional pusher piston block was necessary, said pistons being actuated by means of solenoids and being installed contiguously to the existing valve block, whereby, while the efficiency of operation was considerably improved with respect to the valve blocks actuated by the timer drum, this device did not solve the problem of providing a valve block which, when used in lieu of the prior art blocks, could be easily adaptable to any glassware forming machine of those existing in the market.
With the advent of the cartridge valve, which in short is a slidable plunger type valve comprising two inner chambers and a plunger, said plunger in a first position thereof communicating the two inner chambers with each other and said plunger in a second position thereof communicating one of said inner chambers with the exterior, the design of the valve blocks could be considerably improved, inasmuch as this type of cartridge valves, appropriately operated by means of pilot air, showed considerable advantages with respect to the mere pistons used in the valve blocks of the prior art, such as that described and claimed in the above mentioned U.S. Pat. No. 4,162,910. Therefore, the operation of the valve blocks for glassware forming machines was rendered more efficient and of more instantaneous response by virtue of the elimination of the purely mechanical operating valves, using instead pneumatical valves which are of faster and more accurate response than said mechanical valves and which, also, do not contain movable parts which may be easily worn out.
Therefore, in U.S. Pat. No. 4,082,108, patented Apr. 4, 1978 to Maul Technology Corporation, a valve block is described which uses the above mentioned cartridge valves, the plungers of which were actuated by means of pilot air controlled through solenoid valves mounted externally of the block, and said block valve of U.S. Pat. No. 4,082,108 was designed in such a way that the valve block contained two separate rows of valves, each of which was provided with chambers within which the cartridge valves operated. Through each row of valves there were associated an operational air feed manifold and an exhaust manifold for operational air, which were handled by the movement of the plungers of the cartridge valves in turn operated by means of the pilot air handled by the solenoid valves external to the valve block, whereby in a position of the plunger of the cartridge valve, the air of the operational air feed manifold towards the operational feed lines to the various parts of the machine, whereas in the other position of the plunger, said operational air lines were communicated with individual exhausts which were connected to the exhaust manifold of the valve block of said patent.
While the valve block of U.S. Pat. No. 4,082,108 considerably improved the efficiency of the valve blocks of the prior art, it still showed serious drawbacks in view of various causes, inter alia, that given the provision of two different manifolds for feeding operational air and two different exhaust manifolds for the operational air, it was necessary to space the two rows of valves of the block by a considerable distance, which increased the size of the block, therefore rendering the same difficult to adapt to the existing machines, whereby certain elements of the machine had to be redesigned to accommodate the said valve block of a larger size in order to integrate the same to a glassware forming multiple station machine.
On the other hand, the provision of pilot air through solenoid valves installed externally of the valve block constituted a considerable disadvantage, in view of the fact that the pilot air lines had to be necessarily long and consequently the response of the cartridge valves to the pneumatic signal sent by the solenoid valves was not as instantaneous as desirable, thereby causing a lag of a number of fractions of a second which, in view of the high speed of these machines, was enough to create the need of dephasing the operation of the machine with respect to the signal in order to compensate for the delay in the signal.
On the other hand, the provision of pilot air control solenoid valves required an externally complex installation and this rendered the installation and the maintenance and operation of said valves more difficult to a considerable extent.
The above mentioned disadvantages of the valve blocks built with cartridge valve chambers were partially overcome by valve blocks in which the solenoid valves were integrally provided in the valve block, whereby the distance of travel of the pilot air was minimized and the resulting signal was practically instantaneous. Thus, for instance, in U.S. Pat. No. 3,918,489, patented Nov. 11, 1975 to Emhart (UK) Limited and equivalent to British Pat. No. 1,415,012 also to Emhart (UK) Limited, a valve block is described which operates with cartridge valves introduced in chambers within the block and having a corresponding plurality of solenoid valves arranged in an additional device integrated to the block, in order to decrease to a considerable extent the distance that the pilot air must move from its source, through the solenoid valve and towards the expansion chamber of the cartridge valve, whereby an instantaneous pilot signal was secured, thereby overcoming the drawbacks shown by the prior art valve blocks, including those described in U.S. Pat. No. 4,082,108, even when the latter was developed after the valve blocks of U.S. Pat. No. 3,918,489. Despite the fact that the valve block of U.S. Pat. No. 3,918,489 is a very compact and practical valve block which satisfactorily solves almost all the problems presented by the prior art blocks, said valve block still shows certain disadvantages, particularly in connection with the arrangement of its elements, in view of the fact that in said valve block it is still necessary to maintain two totally spaced valve rows with an exhaust manifold inbetween and, in connection with the operational air inlets to the cartridge valves, these inlets are normally individual or at most depend from two inner but separate manifolds, which force said blocks to be relatively large. This affected the practicality of the block to be used in lieu of other valve blocks in the majority of glassware forming machines.
As to the pilot solenoid valves which are integrated to the block itself, said valves, in view of a manual piloting device which they must contain, angularly arranged with respect to said solenoid valves, required considerable room whereby the piolt air block had to be very thick, thus increasing the cost of manufacture of the block and rendering its installation in reduced spaces difficult. Also, the pilot air channels had to be necessarily long and consequently wider, which produced a higher air consumption and a deficiency as to the instantaneous characteristic that the pilot signal must have in order to operate the cartridge valve so as to obtain an instantaneous response in the operational air, inasmuch as the various mechanisms of glassware manufacturing machines must be moved at accurate times and with extremely high speeds, thus requiring a considerable accuracy in the pilot signal, which is not obtainable with the design of the valve block of U.S. Pat. No. 3,918,489. The provision of separate operational air inlets, or the provision of an air inlet manifold with two plenums or exhaust manifolds, also caused the volume of the valve block to this patent to be considerable, which together with the considerable size that the pilot air block must have, produced a very bulky and heavy valve block, not adaptable in practice to many existing glassware forming machines. On the other hand, the spacing between the two rows of valves contained by the block of U.S. Pat. No. 3,918,489, rendered it difficult to enclose the solenoid valves within a pressurized chamber to avoid any pollution by dust or fumes and the like, which caused a deficient performance of the solenoid valves with the consequent stops or delays in the machines. The arrangement of the handles for manual actuation of the solenoid valves, at right angles with respect thereto and at a different face of the block, was also a considerable disadvantage. Also, said manual actuating mechanisms were, in the device of the above patent, very cumbersome and inefficient and slow to be handled by the operator, which caused inefficiency situations when the operator was unable to move the actuator with sufficient speed to open or close the solenoid valves at a given time.
All the above mentioned problems shown by the prior art valve blocks have been duly solved by a valve block which is described in copending U.S. patent application Ser. No. 330,919, filed in the name of the same applicants on the same date hereof and clamping priority on Mexican patent application No. 185,294 filed Dec. 16, 1980, which shows a highly improved valve block, acting in a similar manner, that is, under the same basic principles of the valve block of U.S. Pat. No. 3,918,489 (or British Pat. No. 1,415,012) which carries out its functions with a highly increased efficiency and without showing the problems shown by the valve block of the above mentioned patents. In effect, said U.S. copending application mentioned above describes a valve block that is constructed by having two staggered rows of valve chambers within which the respective cartridge valves operate, and said block comprises a block having only one single operational air feed manifold, said manifold having a generally rectangular cross-section and extending along the length of said valve block, whereby the valve chambers open on one side of said manifold directly without the need of intermediate conduits which would cause pressure drops, said chambers opening at their other ends on one outer face of the valve block. Said valve chambers are provided by means of an intermediate block which is attached to the above mentioned block or primary block, wherein said chambers are suitably provided by means of bores that directly open towards the manifold and towards the outer face of the block. Of course, suitable conduits are also provided in this intermediate block to connect each one of said valve chambers with the exterior of the block. A secondary block is also provided directly attached to said intermediate block, on which a plurality of solenoid valves also arranged in a staggered array are provided, with a pair of conduits or manifolds for feeding pilot air running along the secondary block and a plurality of very thin and short conduits for pilot air towards the expulsion chamber of the cartridge valves, said secondary block or pilot air block being thin in order to shorten the length of the path to be travelled by the pilot air. The solenoid valves of said improved block are of very small capacity by virtue of the fact that only an opening signal must be transmitted to the valve in order to feed pilot air into the cartridge valve chamber, and this arrangement provides shorter pilot air paths as well as a smaller air consumption, also securing an instantaneous signal in view of the short distance that the pilot air must travel and in view of the fact that the operational air is directly communicated from the manifold connecting the same to the respective valve chambers which contain the cartridge valves, which provides for a flow of air without any appreciable pressure drop towards the various mechanisms of the machine, each one of which is connected by means of the well known needle valve system with each one of the valve chambers of the block of said invention. The above, besides achieving a practically instantaneous response of the mechanisms with respect to the time in which electrical signals are received through the solenoid valves, also provides a very compact block which is adaptable to any type of glassware manufacturing machine and, also, said block may be manufactured by modification of already existing blocks by means of small adaptations which do not require the exercise of intricate techniques or the use of high labor.
While the block of the above mentioned copending U.S. application totally solves the problems presented by the prior art blocks, it still requires the installation of a pilot air system which, regardless of its efficiency, causes a delay, however small, whereby the signal is not at all instantaneous, and it has been the purpose of the workers in the art to seek a device which, without loosing the safety and accuracy of the pilot air systems, may replace the same with advantages by improving the instantaneous characteristic of the signal
Another important drawback of the prior art valve blocks is that two considerable operational effects may occur when the pilot air is dirty, namely, that the dirt may prevent the pilot valve from accomplishing a tight seal which maintains the corresponding mechanism actuated; and that the humidity causes corrosion in the cartridge valves thus considerably reducing the life thereof.